1. Field of the Invention
This invention relates in general to golf balls and more particularly to an improved golf ball having the fused junction and molding flash, where two cover blanks are used to form the cover, extending around the ball in a wave form configuration to improve the bonded strength of the fused junction and to permit greater latitude in arranging dimple patterns thereon.
2. Description of the Prior Art
The usual golf ball manufacturing techniques includes the winding of an elastomeric band about a spherical elastomeric core to form the body of the golf ball. Another technique being employed by some manufacturers is to form a one-piece spherical body of a suitable elastomeric material. In either case, the golf ball body is moldingly encapsulated in a cover of synthetic resin, or plastic, such as the material known in the art as Surlyn which is a registered trademark of the Dupont Co.
The cover molding operation is accomplished by using a pair of hemispherical molds each of which has an array of protrusions machined or otherwise provided in its cavity, and those protrusions form the dimple pattern on the periphery of the golf ball during the cover molding operation. A pair of hemispherical cover blanks, of the above mentioned synthetic resin material, are placed in a diametrically opposed position on the golf ball body, and the body with the cover blanks thereon are placed in the hemispherical molds, and then subjected to a molding operation. The combination of heat and pressure applied during the molding operation results in the cover blanks being fused to the golf ball body and to each other to form a unitary one-piece cover structure which encapsulates the golf ball body. In addition, the cover blanks are simultaneously molded into conformity with the interior configuration of the hemispherical molds which results in the formation of the dimple pattern on the periphery of the golf ball cover.
As in all molding operations, when the golf ball is removed from the hemispherical molds subsequent to the molding operation, it will have molding flash, and possibly other projecting surface imperfections thereon. The molding flash will be located at the fused circular junction of the cover blanks and the parting line of the hemispherical molds. The molding flash will therefore be on a great circle of the spherical golf ball, and that great circle is sometimes referred to in the golf ball art as the "equator" of the golf ball.
The molding flash and possible other projecting surface imperfections, needs to be removed and this is normally accomplished by a grinding operation. Due to the need for grinding, the molding operation must be accomplished in such a manner that the molding flash is located solely on the surface of the golf ball and does not extend into any of the dimples. In other words, a grinding operation cannot reach into the dimples of the golf ball to remove the molding flash without ruining the golf ball cover.
Therefore, the prior art hemispherical molds are fabricated so that the protrusions formed therein are set back from the circular rims, or mouths of their cavities. This results in the equator of a molded golf ball being devoid of dimples and the molding flash being located solely on the smooth surface provided at the equator of the golf ball.
In addition to facilitating the grinding-off of molding flash, the protrusions formed in the cavities of the hemispherical molds are set back from the circular mouths of the molds to facilitate removal of the molds from the molded golf ball after completion of the molding operation. If projections were formed at the circular mouths of the molds, they would extend into dimples formed at the equator of the golf ball, and pulling the molds off of the golf ball in directions perpendicular to the plane of the equator would be difficult, if not impossible.
As is well known, the dimple pattern of a golf ball is a critical factor insofar as the flight characteristics of the ball are concerned. The dimples determine the lift and flight stability of the golf ball. When a golf ball is struck properly, it will spin about a horizontal axis and the air friction and air currents produced by the dimples of the spinning ball will act on the ball and thus determine the lift and flight stability thereof.
In order for a golf ball to achieve optimum flight stability, its dimples must be disposed symmetrically relative to a plane that is perpendicular to its horizontal axis of rotation. Any deviation from such symmetry will result in unequal air friction and air currents acting on the ball thus causing it to deviate from the intended flight path.
In that prior art golf balls are manufactured with a smooth surface along a great circle, or equator of the ball, the only possible symmetrical arrangement of the dimple patterns that can be provided on these balls is relative to the equator. In other words, the dimple arrays on the hemispherical portions on opposite sides of the equator can be symmetrically arranged with respect to each other. If such symmetry is achieved during manufacturing of a prior art golf ball, the dimple arrays will, of course, be symmetrical relative to the equator and possibly relative to a great circle which is perpendicular to the equator. The dimple pattern cannot possible be symmetrical relative to any other great circle on the spherical surface of the prior art golf balls in that the smooth surface of the equator will interrupt and thus destroy the symmetry.
Therefore, there are only two ways that a spinning golf ball of this prior art type of golf ball can possibly achieve optimum flight stability. The first condition wherein optimum flight stability could possibly be achieved is when the equator lies in the plane which is perpendicular to the horizontal axis of rotation, with the second being when the equator is oriented so that the horizontal axis of rotation passes diametrically through the equator.
Therefore, since the prior art golf balls are manufactured with a smooth surface equator, they are limited as to the symmetry of their dimple patterns and as a result, a very low percentage of golf ball flights will achieve optimum flight stability. In addition, in that the prior art golf balls are made by fusing the two hemispherical cover blanks along a great circle, that circular fused junction is a weak spot in the cover of such golf balls.
Therefore, a need exists for a new and improved golf ball, with a method and molds for making same, which overcome some of the problems and shortcomings of the prior art.